#include #include #include #include #include #include #include #include #include #include #include #include #include #include #define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl; #define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } using namespace std; typedef long long ll; template vector> vec2d(int n, int m, T v){ return vector>(n, vector(m, v)); } template vector>> vec3d(int n, int m, int k, T v){ return vector>>(n, vector>(m, vector(k, v))); } template void print_vector(vector v, char delimiter=' '){ if(v.empty()) { cout << endl; return; } for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter; cout << v.back() << endl; } using mint = atcoder::modint998244353; ostream& operator<<(ostream& os, const mint& m){ os << m.val(); return os; } mint dp[3000][3000]; int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << setprecision(10) << fixed; int c, x; cin >> c >> x; if(x == 0){ cout << mint(1)/(c+1) << endl; return 0; } dp[0][0] = 1; int mx = 0; for(int i = 1; c+i-1 < x; i++){ chmax(mx, i); for(int k = 0; k < i; k++){ if(dp[i-1][k].val() == 0) continue; int candidate = c+i-k; mint p = mint(candidate)/mint(c+i); // cout << i << ' ' << k << ' ' << p << endl; dp[i][k+1] += dp[i-1][k]*p; dp[i][k] += dp[i-1][k]*(1-p); } } mint ans = 0; for(int used = 0; used <= x; used++){ int k = x+1-used; ans += dp[mx][used]*(k-1)/k; // cout << k << ' ' << dp[mx][used] << endl; } cout << ans << endl; }